1. Field of the Invention
This invention relates to the field of collapsible structures for such applications as portable garages, greenhouses, military camouflage coverings and tents. The structure is intended to be conveniently assemblable, yet strong enough to stand up to rough handling and long use in exposed locations.
2. Description of the Prior Art
The prior art discloses a number of inventions related to collapsible structures. In addition to tent structures, such diverse applications as baby carriages, umbrellas, aircraft hangers, automobile covers and folding corridors employ skin members stretched over rib members. These structures each attempt to deal with the common problems of providing a lightweight, conveniently assemblable yet strong structure. Prior art structures may be divided into categories according to the method of supporting joist members which in turn suppport the flexible skin. For example, support members may be connected rigidly or pivotally, on an axis or along a sliding track. The present invention supports rib or joist members pivotally at equally spaced locations around hub members located at either side of the unit.
A second characteristic for comparison of prior art structures is the method of holding the joist and skin assembly in an open or closed position. The covering skin is often flexible, e.g. plastic, and will itself provide a certain amount of tension, for holding the structure in position. This scheme is used for tent structures and umbrellas. As applied to automobile coverings, the flexible skin is often stretched over the vehicle and attached under tension to the bumpers at either end. In addition, a number of locking schemes are disclosed by the prior art. Non-extensible members may be connected between joist members to secure the joist members at spaced intervals over which the skin is stretched. The present invention solves the locking problem by providing a combination spring/locking mechanism which is stable either in an open or closed position. Although a springy skin may be employed, a less-extensible, heavy duty fabric is preferred.
The present invention employs the advantages of the prior art's flyweight tent structures as well as the advantages of the more substantial building-like structures. The present invention comprises a substantial structure, yet one which is conveniently assembled, disassembled and transported. The construction is simple yet strong, and is particularly suited to long term installation in exposed areas.